The fraction of CD39 expressing CD4+ Teff cells significantly increased in prostate cancer patients before therapy (3.32% mean with 1.32–5.32% 95% CI before therapy and 1.45% mean with 0.64–2.26% 95% CI in healthy controls) and levels further increased 3 months after seed implantation (5.33% mean with 2.37–8.30% 95% CI), followed by a slow decrease. The gene discussed is ENTPD1; the disease is prostate cancer.